Poor reading ability has profound cognitive, emotional, and behavioral consequences for the developing child, and-if unremediated-eventually has economic consequences for the adult. Indeed, the 2003 report on Adult Literacy and Life Skills (Statistics Canada and OECD, 2005) estimates that 51percent of US adults aged 16-25 can read only simple texts and make only low-level inferences, a level termed below-basic, which is insufficient for attaining advanced educational and occupational goals. These statistics point to the need for understanding factors contributing to poor reading ability beyond the single-word level in the adult population. This application brings together findings from three largely independent research communities (memory, adult sentence and discourse processing, and reading disability) and creates a novel approach towards understanding poor comprehension. Whereas, the bulk of linguistically-based research into sentence and text-level comprehension has emphasized a limited set of general cognitive capacities (especially working memory capacity) as the source of comprehension difficulty, and focused primarily on the college-level population, this project is built around an architectural framework that emphasizes memory retrieval as the mechanism connecting word- reading skills and higher-level integrative skills. Building on memory research pointing to a severely limited active memory capacity, even for skilled readers, we assume that comprehension is primarily determined by the successful retrieval of information from passive memory. Thus, in our Specific Aim 1 we investigate the conditions leading to successful retrieval, including the way that different types of linguistic cus (phonological, morphological, syntactic, semantic, pragmatic) are combined, and the conditions leading to failed retrieval- namely the presence of memory interference. Our Specific Aim 2 combines long standing conclusions from memory research, suggesting that sensitivity to interference will be determined by the quality of to-be-retrieved representations, with research in reading disability, arguing that individuals will vary in the average quality of their word representations, which are determined by their reading experience and facility for processing different types of linguistic information. Finally, our Specific Aim 3 investigates the neurologica bases of sensitivity to retrieval interference, with primary focus on the neural networks that link skilled word reading to higher level processing, and the contribution of regions responsible for mediating interference at each level, especially left inferior frontal gyrus. We include both college and non-college community-based individuals (age 16-24), to provide a more representative sample of reading ability than in previous studies and thus increase the impact of our potential findings. In addition, we recruit a sample of beginning readers (age 7-9) for an initial investigation of the development of retrieval and sensitivity to interference. We expect tht this project will result in a new conception of sources of individual variability in reading comprehension, and a deeper understanding of how these develop in childhood and persist into adulthood.